Joomla is a great content management system for building company websites. Firstly, a lot of people know and love Joomla and this allows companies to not be dependent on one web designer. (It's easy to find replacements.) Secondly, Joomla is on my top-three list of favorite technologies because it is a content management system that's open source with a ton of available extensions, templates, and a large fan base.
Let me take that sentence apart and explain it.
One of the first aspects of Joomla I appreciate is that it's open source. Open source software is free and publically available. Anyone can download the source code, modify it, and use it. A community of people decides the future of the software, and a major corporation doesn't profit. Besides the no-cost feature of open-source software, there's a philosophical ideal associated with open source software that makes it appealing.
Content management system (CMS)
A content management system provides the ability to easily manage large quantities of data while keeping the formatting and presentation of that data separate. Imagine a filing cabinet filled with single sheets of paper with simple text on them with an occasional image. Each sheet of paper is filed in a manila folder and each manila folder is filed in a big, green folder. That's the content.
So, if you need to look at one of those sheets of paper, you pull it up. Right before you see the text on that paper, however, a magic filter sits on top of the paper and adds fonts, bolding, italics, different sizes, colors, and shapes. The magic filter is the formatting and it presents the content to you.
The beauty of this separation of content from formatting allows a web designer to make changes to a website in one spot and have those changes affect the entire site all at once.
By itself, Joomla provides a fair amount of features. With the available extensions, however, Joomla can do much more. Extensions are additional programs that attach to Joomla and make the web site do more than it did before. There are currently over 3,000 extensions available for Joomla including shopping carts, search engine optimization, social media integration, news feeds, list management, membership management, and even games.
Remember the magic filter that the website applies to the data to present it to you? The formatting is controlled by Joomla templates. Free templates are plentiful on the Internet, as are commercial, professionally designed templates. There's a great selection to choose from and you don't have to spend a lot of time deep in CSS code.
Large fan base
A lot of people like Joomla and a lot of people use it. Many of these people help the Joomla community by providing technical support, writing documentation, designing templates, writing extensions, and improving and maintaining the Joomla source code. When I last checked, the Joomla website said there were over 200,000 users registered in the Joomla forums. What does a large fan base mean? Joomla is staying around for a while and help is available if you need it.
All of these things, the fan base, the CMS aspect, the extensions, and the templates, are enough to like Joomla. From a business standpoint, Joomla is great. If your web developer becomes unreachable, you can easily find someone else to work and maintain the site. With a tiny bit of training, a business owner could even maintain their own site.